Recent concerns about human infection with avian strains of influenza have led to widespread efforts to enhance our ability to respond to an influenza pandemic. Public health agencies and healthcare institutions have assumed that influenza-specific antiviral therapy will be an important component of an initial response to an emerging pandemic. Oseltamivir has emerged as the antiviral drug that is anticipated to be of greatest potential benefit for patients infected with either seasonal or pandemic influenza in the future. Limited data exist to support the ability of influenza-specific therapies to alter the outcomes of children hospitalized due to infection with either seasonal or pandemic strains of influenza virus. The efficacy of oseltamivir in children has been exclusively studied in the outpatient setting. Furthermore, during a pandemic, it is anticipated that the demand for oseltamivir will exceed supply; thus understanding the benefits, risks, and costs associated with use of this antiviral agent in patients with serious influenza infection will be helpful in times of shortage. We propose to examine the outcomes, costs, and adverse drug events associated with the use of oseltamivir for the treatment of influenza in hospitalized children. Our specific aim was designed to determine if treatment with oseltamivir improves the clinical outcomes of children hospitalized with influenza. Furthermore, we have developed two secondary aims to: (1) assess the occurrence of drug related adverse events, specifically neurologic adverse events, associated with the use of oseltamivir in children hospitalized with influenza; and (2) to determine if treatment with oseltamivir reduces direct medical costs associated with influenza hospitalization. We will conduct a multi-site, retrospective cohort study using data abstracted from the PHIS database. The PHIS database is a comprehensive, comparative pediatric database that was created by Child Health Corporation of America (CHCA) for member hospitals. It contains clinical and financial details of more than six million patient cases. Specifically, the database contains the diagnosis and procedure codes and billed transaction/utilization data of inpatient and outpatient hospital encounters among the 40 PHIS owner children's hospitals nationwide. We anticipate this analysis will be generalizable to children hospitalized anywhere in the United States. Recognizing the potential threat of pandemic influenza, virtually all health care agencies in the United States are currently developing plans to provide care to large numbers of infected patients. Because the disease is likely to be widespread before a vaccine specific for a pandemic strain of influenza is available, antiviral medications are anticipated to be a critical component of the early response to a pandemic. The proposed project will enhance our understanding of influenza-specific antiviral therapy and its ability to alter the outcomes of children hospitalized with the influenza virus. [unreadable] [unreadable] [unreadable]